No Power In LCD Monitor
Whenever you switch “On” LCD Monitor and the Power LED indicator doesn’t lit don’t always assume it was the power supply problem. You must understand that the source of voltage to the power LED indicator was from the Mainboard particularly from the MCU. If the MCU have problem or the internal DATA had been corrupted then it won’t be able to send an “On” signal to the LED. This problem happened many times in the ACER and the BenQ LCD Monitor and replacement of the Main board solved the problem.
In order to isolate whether is the Mainboard or the power supply problem, you just need to measure the output voltages from the power supply. If you got all the voltages to the main board and the LED does not light then suspect a faulty Main board. If there is no voltages at all then suspect the power supply fault. Be remind that i had came across before the Power On/Off micro switch button failure and with a new replacement brought back the display-of course the LED lit! You can easily test the On/Off button using an ohmmeter or even with the help of continuity check.